JAK-STAT (Janus kinase-signal transducer and activator of transcription) signal pathway is a cytokine-stimulated signal transduction pathway found in recent years and is involved in many important biological processes such as cell proliferation, differentiation, apoptosis and immune regulation (Aaronson, D S et al. Science 2002, 296, 1653-1655; O'Shea, J J et al. Nat. Rev. Drug Discovery 2004, 3, 555-564). Compared with other signal pathways, this signal pathway is relatively simple. It mainly consists of three components which area tyrosine kinase related receptor, a tyrosine kinase JAK and a transcription factor STAT. JAK (Janus Kinase), a class of molecules in the cells, is rapidly raised on the receptor and activated, after receiving signals from the upstream receptor molecules. The activated JAK catalyzes tyrosine phosphorylation of the receptor, and phosphorylated tyrosine on the receptor molecules is the recognition and binding site of STAT SH2, a class of signal molecules. Tyrosine phosphorylation also occurs after STAT binds to the receptor. Tyrosine phosphorylated STAT forms dimer and enters the nucleus. As an active transcription factor, dimeric STAT molecules directly affect the expression of related genes, thereby changing the proliferation or differentiation of target cells.
The JAK-STAT pathway widely presents in various tissue cells in vivo, and plays an important role in differentiation, proliferation and anti-infection of lymphocyte lines and is involved in the interaction and signal transduction of various inflammatory factors (Kiesseleva T. et al. J. Gene, 2002, 285, 1-24). Abnormal activation of this pathway is closely related to many diseases. To find and screen JAK inhibitors can help further study the regulation mechanism of JAK-STAT and provide new drugs and methods for the prevention and treatment of related diseases.
The formation, growth, invasion and metastasis of tumors are related to JAK-STAT signal transduction pathway. The activation of STATs in normal signal transduction is rapid and transient, and the persistent activation of STATs is closely related to the malignant transformation process of cells (Buettner R. et al. Clin. Cancer Res. 2002, 8(4), 945-954). STAT3 is the focal point of many oncogenic tyrosine kinase signal pathways such as EGFR, IL-6/JAK and Src etc. and is activated in many tumor cells and tissues such as breast cancer, ovarian cancer, head and neck squamous cell carcinoma cancer, prostate cancer, malignant melanoma, multiple myeloma, lymphoma, brain tumor, non-small cell lung cancer and various leukemias (Niu G. et al. Oncogene 2002, 21(13), 2000-2008). JAK-STAT pathway inhibitor belongs to PTK inhibitors, and the enzyme is a member of the oncogene protein and proto-oncoprotein family and plays an important role in the normal and abnormal proliferation of cells. The development and growth of tumors cannot be separated from PTK, therefore, JAK-STAT pathway inhibitor inhibits tumor growth by antagonizing PTK and has obvious anti-tumor effect (Mora L. B. et al. J. Cancer Res. 2002, 62(22), 6659-6666).
In addition, recent studies have shown that organ transplant rejection, psoriasis, tissue and organ fibrosis, bronchial asthma, ischemic cardiomyopathy, heart failure, myocardial infarction, hematological and immune system diseases are all closely related to JAK-STAT signal transduction pathway. This signal pathway is not only important for maintaining the normal physiological function of cells, but also plays an important regulatory role in the occurrence and development of the disease.
The family of fibroblast growth factor receptors belongs to a new family of receptor kinases, and includes four receptor subtypes encoded by four closely related genes (FGFR-1, 2, 3 and 4) and some isomeric molecules which participate in regulating physiological processes in living organisms through forming ternary complexes with fibroblast growth factor (FGF) and heparan sulfate and then triggering a series of signal transduction pathways. FGFR has a wide range of physiological and pathological functions in the body: (1) Embryonic development. Studies have shown that during the process of embryonic development, FGFR signal transduction is crucial for most organ development and embryonic pattern formation. (2) Cell division, migration and differentiation. FGFR, which stimulates cell proliferation and is involved in the regulation of cell transformation during pathological process, has many parallel pathways that enable FGFR-mediated signal transduction of cell division as evidenced by many studies (J. K. Wang et al., Oncogene 1997, 14, 1767-1778.). (3) Bone disease. Bone growth and differentiation are also regulated by the FGF family, and mutations in FGFR can lead to skeletal deformities (R. Shang et al., Cell 1994, 78, 335-342.). (4) Tumor development. FGFR promotes the migration, proliferation and differentiation of endothelial cells and plays an important role in the regulation of vascularization and angiogenesis. Uncontrolled angiogenesis may lead to the development of tumors and the growth of metastases (J. Folkman. Nat. Med. 1995, 1, 27-31.).
FMS-like tyrosine kinase 3 (FLT3) is a family member of receptor tyrosine kinase III (RTK III), and is composed of three parts, extracellular region, intracellular region and transmembrane region. It is first expressed in human hematopoietic stem cells, where FLT3 interacts with its ligand FL to stimulate or act on stem cells, which is of great importance for the growth and differentiation of stem cell. FLT3 kinase has wild type FLT3-WT and its major activating mutations FLT3-ITD and FLT3-D835Y. FLT3 is mainly expressed in the precursors of normal myeloid cells, but its abnormal expression is also found in a large part of acute myeloid leukemia (AML). In recent years, many large sample studies have confirmed that activating mutations of FLT3 play a very important pathological role in the pathogenesis and progression of acute myeloid leukemia. FLT3 has become an important target for the treatment of acute myeloid leukemia.
Src family kinase (SFK) is a family of non-receptor tyrosine kinases, including c-Src, LYN, FYN, LCK, HCK, FGR, BLK, YES and YRK, among which LYN kinase has two subtypes of LYNα and LYNβ, and LYN kinase and its two subtypes can cause similar intracellular tyrosine phosphorylation. According to the amino acid sequence, SFK can be divided into two subfamilies: a subfamily of c-Src, FYN, YES and FGR, widely expressed in different tissues; the other subfamily of LCK, BLK, LYN and HCK, closely related to hematopoietic cells. SFK is linked to multiple in vivo signal transduction pathways and is activated by growth factors, cytokines and immune cell receptors, G-protein coupled receptors, and integrins and other cell adhesion molecules, and then activating the corresponding signal transduction pathway, causing a variety of physiological effects of the cell. The activity of SFK mainly includes the regulation of cell morphology, cell motility, cell proliferation and survival. Abnormal activation and expression of these kinases lead to the development and progression of a wide range of diseases, such as a large number of solid tumors, a variety of hematological malignancies and some neuronal pathologies. Therefore, finding SFK inhibitors is a promising research topic in the field of medicinal chemistry.